FMSLogo Code

Change an #if into an #ifdef to fix a compiler warning

Remove the call to GetVersionEx() and everything which depends on it. The only remaining use of this was to determine if HALFTONE was supported by SetStrechBlitMode(). On Windows 95, this is not supported and so COLORONCOLOR was used. Since FMSLogo no longer supports Windows 95, it can assume that HALFTONE is supported.

This was done to clean up the code, remove untestable portions, and remove unnecessary platform-dependent code to assist with the GNU/Linux port.

Remove some unneeded #defines that duplicated what should have been in windows.h, but now generated compiler warnings.

This was needed to be able to compile the screensaver with an old version of MinGW whose libc didn't include instructions that weren't implemented in the original Pentium CPUs. As of version 7.0, FMSLogo no longer supports those machines or that compiler, so #defines can be safely removed (and the compiler warnings along with them).

Fix a reference to a bug number in the source code (the bug numbers changed when SourceForge.net was bought by DICE and they redid the database backend).

Minor refactoring to improve readability:
* Convert a global variable into a stack variable to better show its scope
* Re-organize TThreeDSolid::DisplayPolygon to compute variables closer to where they are used.
* Add some comments.

Remove an unused manifest constant.

Reimplement YESNOBOX using platform-independent wxWidgets API, instead of win32 functions. This was done to make the code accessible on GNU/Linux.

A side-effect is that question mark icon won't appear on Vista or later (an intentional choice by wxWidgets to follow Microsoft Windows UI guidelines). Since I agree with the UI guidelines, I don't consider this to be a regression.

Fix a regression in the screensaver where using DIALOGFILEOPEN created the window behind the screen window, making it invisible. The regression was introduced when the screensaver was ported to wxWidgets.

I had been fixing this class of bug by using the wxSTAY_ON_TOP style for each of the dialog boxes that a Logo command can create, but ran into a problem in DIALOGFILEOPEN where this had no effect (the dialog isn't a real wxWidgets dialog box, but a proxy to a common control). After some experimentation, I settled on a new strategy, which is to lower the screensaver window so that any windows created after it would be on top of it.

Factor common code that's shared between DIALOGFILEOPEN and DIALOGFILESAVE into a helper function named "dialogfile_helper".

Add regression tests for DIALOGFILEOPEN and DIALOGFILESAVE.